1. Field of the Invention
The present invention relates to an organic electroluminescence (EL) display device.
2. Description of the Related Art
In recent years, display devices using organic electroluminescence (EL) elements have vigorously been developed, by virtue of their features of self-emission, a high response speed, a wide viewing angle, a high contrast, small thickness and light weight.
In the organic EL element, holes are injected from a hole injection electrode (anode), electrons are injected from an electron injection electrode (cathode), and the holes and electrons are recombined in a light emitting layer, thereby producing light. In order to obtain full-color display, it is necessary to form pixels which emit red (R) light, green (G) light and blue (B) light, respectively. It is necessary to selectively apply light-emitting materials, which emit lights with different light emission spectra, such as red, green and blue, to light-emitting layers of organic EL elements which constitute the red, green and blue pixels. As a method for selectively applying such light-emitting materials, there is known a vacuum evaporation method. In the case of forming films of low-molecular-weight organic EL materials by such a vacuum evaporation method, there is a method in which mask evaporation is performed independently for respective color pixels by using a metallic fine mask having openings in association with the respective color pixels (see, e.g. Jpn. Pat. Appln. KOKAI Publication No. 2003-157973).
In the mask evaporation method using the metallic fine mask, however, pixels become very fine in the case where a high fineness (resolution) is required for the display device. As a result, a so-called color mixture defect, by which light-emitting materials of respective colors are mixed, occurs frequently, and full-color display with high fineness is difficult realize.